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// Copyright © 2026 Mikhail Hogrefe
//
// This file is part of Malachite.
//
// Malachite is free software: you can redistribute it and/or modify it under the terms of the GNU
// Lesser General Public License (LGPL) as published by the Free Software Foundation; either version
// 3 of the License, or (at your option) any later version. See <https://www.gnu.org/licenses/>.
use crate::integer::Integer;
use crate::natural::Natural;
use core::ops::{Shl, ShlAssign, Shr, ShrAssign};
use malachite_base::num::arithmetic::traits::UnsignedAbs;
use malachite_base::num::basic::traits::Zero;
fn shl_unsigned<T>(x: Integer, bits: T) -> Integer
where
Natural: Shl<T, Output = Natural>,
{
Integer {
sign: x.sign,
abs: x.abs << bits,
}
}
fn shl_unsigned_ref<'a, T>(x: &'a Integer, bits: T) -> Integer
where
&'a Natural: Shl<T, Output = Natural>,
{
Integer {
sign: x.sign,
abs: &x.abs << bits,
}
}
macro_rules! impl_shl_unsigned {
($t:ident) => {
impl Shl<$t> for Integer {
type Output = Integer;
/// Left-shifts an [`Integer`] (multiplies it by a power of 2), taking it by value.
///
/// $$
/// f(x, k) = x2^k.
/// $$
///
/// # Worst-case complexity
/// $T(n, m) = O(n + m)$
///
/// $M(n, m) = O(n + m)$
///
/// where $T$ is time, $M$ is additional memory, $n$ is `self.significant_bits()`, and
/// $m$ is `bits`.
///
/// # Examples
/// See [here](super::shl#shl).
#[inline]
fn shl(self, bits: $t) -> Integer {
shl_unsigned(self, bits)
}
}
impl<'a> Shl<$t> for &Integer {
type Output = Integer;
/// Left-shifts an [`Integer`] (multiplies it by a power of 2), taking it by reference.
///
/// $$
/// f(x, k) = x2^k.
/// $$
///
/// # Worst-case complexity
/// $T(n, m) = O(n + m)$
///
/// $M(n, m) = O(n + m)$
///
/// where $T$ is time, $M$ is additional memory, $n$ is `self.significant_bits()`, and
/// $m$ is `bits`.
///
/// # Examples
/// See [here](super::shl#shl).
#[inline]
fn shl(self, bits: $t) -> Integer {
shl_unsigned_ref(self, bits)
}
}
impl ShlAssign<$t> for Integer {
/// Left-shifts an [`Integer`] (multiplies it by a power of 2), in place.
///
/// $$
/// x \gets x2^k.
/// $$
///
/// # Worst-case complexity
/// $T(n, m) = O(n + m)$
///
/// $M(n, m) = O(n + m)$
///
/// where $T$ is time, $M$ is additional memory, $n$ is `self.significant_bits()`, and
/// $m$ is `bits`.
///
/// # Examples
/// See [here](super::shl#shl_assign).
#[inline]
fn shl_assign(&mut self, bits: $t) {
self.abs <<= bits;
}
}
};
}
apply_to_unsigneds!(impl_shl_unsigned);
fn shl_signed_ref<'a, U, S: Copy + Ord + UnsignedAbs<Output = U> + Zero>(
x: &'a Integer,
bits: S,
) -> Integer
where
&'a Integer: Shl<U, Output = Integer> + Shr<U, Output = Integer>,
{
if bits >= S::ZERO {
x << bits.unsigned_abs()
} else {
x >> bits.unsigned_abs()
}
}
fn shl_assign_signed<U, S: Copy + Ord + UnsignedAbs<Output = U> + Zero>(x: &mut Integer, bits: S)
where
Integer: ShlAssign<U> + ShrAssign<U>,
{
if bits >= S::ZERO {
*x <<= bits.unsigned_abs();
} else {
*x >>= bits.unsigned_abs();
}
}
macro_rules! impl_shl_signed {
($t:ident) => {
impl Shl<$t> for Integer {
type Output = Integer;
/// Left-shifts an [`Integer`] (multiplies it by a power of 2 or divides it by a power
/// of 2 and takes the floor), taking it by value.
///
/// $$
/// f(x, k) = \lfloor x2^k \rfloor.
/// $$
///
/// # Worst-case complexity
/// $T(n, m) = O(n + m)$
///
/// $M(n, m) = O(n + m)$
///
/// where $T$ is time, $M$ is additional memory, $n$ is `self.significant_bits()`, and
/// $m$ is `max(bits, 0)`.
///
/// # Examples
/// See [here](super::shl#shl).
#[inline]
fn shl(mut self, bits: $t) -> Integer {
self <<= bits;
self
}
}
impl<'a> Shl<$t> for &Integer {
type Output = Integer;
/// Left-shifts an [`Integer`] (multiplies it by a power of 2 or divides it by a power
/// of 2 and takes the floor), taking it by reference.
///
/// $$
/// f(x, k) = \lfloor x2^k \rfloor.
/// $$
///
/// # Worst-case complexity
/// $T(n, m) = O(n + m)$
///
/// $M(n, m) = O(n + m)$
///
/// where $T$ is time, $M$ is additional memory, $n$ is `self.significant_bits()`, and
/// $m$ is `max(bits, 0)`.
///
/// # Examples
/// See [here](super::shl#shl).
#[inline]
fn shl(self, bits: $t) -> Integer {
shl_signed_ref(self, bits)
}
}
impl ShlAssign<$t> for Integer {
/// Left-shifts an [`Integer`] (multiplies it by a power of 2 or divides it by a power
/// of 2 and takes the floor), in place.
///
/// $$
/// x \gets \lfloor x2^k \rfloor.
/// $$
///
/// # Worst-case complexity
/// $T(n, m) = O(n + m)$
///
/// $M(n, m) = O(n + m)$
///
/// where $T$ is time, $M$ is additional memory, $n$ is `self.significant_bits()`, and
/// $m$ is `max(bits, 0)`.
///
/// # Examples
/// See [here](super::shl#shl_assign).
fn shl_assign(&mut self, bits: $t) {
shl_assign_signed(self, bits)
}
}
};
}
apply_to_signeds!(impl_shl_signed);